This invention relates to an alarm system, and more particularly relates to an alarm system which issues an alarm when a vehicle fitted with an odometer has traveled a certain predetermined distance.
Such alarms are desirably fitted to modern vehicles for a variety of reasons. For instance, in the U.S.A. nowadays many, vehicles are fitted with oxygen sensors which have to be checked every 30,000 miles. Thus an alarm device is needed for warning the driver that this predetermined distance has been traversed.
In FIG. 1 of the accompanying drawings is shown a conventional type of alarm system of this sort. The drive gear 31 of the conventional odometer 30 is provided with a projection 34 which engages with a microswitch 36 and actuates it each time the drive gear 31 rotates. That is, the drive gear 31 is engaged with the rotating shaft 32 of which rotation is transmitted to the wheel 33-1, and subsequently to the wheels 33-2 through 33-6. The boss 31a on the drive gear 31 is provided with the projection 34. A microswitch 36 is provided on the frame 35, so that at each rotation of the drive gear 31 the projection 34 may press the contact 36a of the microswitch 36. The counter 37 counts the number of times the microswitch 36 is actuated, and when this number reaches a certain predetermined number the light 38 is lit, indicating that the vehicle has covered the predetermined mileage.
Such a system is expansive to make, because the counter 37 must be provided; and furthermore the counter 37 requires some space.